Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

摘要

It has been a tremendous challenge to manufacture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the requirements of high-energy laser systems.The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP.This study investigates the room temperature creep-deformation of KDP crystals with the aid of nanoindentation.A stress analysis was carried out to identify the creep mechanism.The results showed that KDP crystals could be plastically deformed at the nanoscale.Dislocation motion is responsible for creep-deformation.Both creep rate and creep depth decrease with decrease in peak force and loading rate.Dislocation nucleation and propagation bring about pop-ins in the loaddisplacement curves during nanoindentation.